SCIT 1408 Applied Human Anatomy and Physiology II - Vessels Chapter 19 A

8/18/2019 SCIT 1408 Applied Human Anatomy and Physiology II - Vessels Chapter 19 A

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Blood Vessels

Blood carried thru closed system of vessels that begins and

ends at the heart

Arteries, arterioles, capillaries, venules, veins

Arteries - away from heart; branch, diverge

Veins - toward the heart; merge, converge

Capillaries- capillary beds in tissues; site of internal

respiration

deliver nutrients, O2 unloading

pic up wastes, CO2 loading


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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsFigure 19.1b

Tunica media(smooth muscle andelastic fibers)

Tunica externa

(collagen fibers)

Lumen

Artery

LumenVein

Internal elastic lamina

External elastic lamina

Valve

(b)

Endothelial cellsBasement membrane

a!illar"

net#or$

Capillary

Tunica intima

% Endothelium% &ubendothelial la"er


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Blood Vessel 'natom"

able 19.1

Conducting!elastic- big, close toheart, pressure reservoirs; e"pand

during systole, # during diastole;

$istributing % to organs,

vasoconstriction; # stretchy

&egulate flow to capillaries

'mallest- ( cell thic; ( rbc in

diameter; ) types

*ormed from united capillaries

+arger lumen than arteries; have

valves; blood reservoirs


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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsFigure 19.

Large veins(ca!acitancevessels)

Largel"m!haticvessels

'rteriovenousanastomosis

L"m!haticca!illar"

*ostca!illar"venule

&inusoid

+etarteriole

erminal arteriole

'rterioles(resistance vessels)

+uscular arteries(distributingvessels)

Elastic arteries

(conductingvessels)

&mall veins(ca!acitancevessels)

L"m!hnode

a!illaries(exchange vessels)

*reca!illar" s!hincter horoughfarechannel

Lymphatic

system

Venous system Arterial systemHeart


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, t"!es of ca!illaries-

( Continuous

2 *enestrated

) 'inusoidal


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7/64Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Fenestrated a!illaries

Figure 19.,b



&inusoids

Figure 19.,c



a!illar" Beds rue ca!ilaries vs shunts

Figure 19./a

Blood flow is regulated by vasomotor

nerves and local chemical conditions



a!illar" Beds Vascular shunts

Figure 19./b

Blood flow is regulated by vasomotor

nerves and local chemical conditions



Venous &"stem- Venules

Venules- from capillary beds that converge

*luids, BCs lea to tissues

.ostcapillary venules

smallest venules

endothelium and a few pericytes

+arge venules

one or two layers of smooth muscle /tunica media0



Venous &"stem- Veins

Veins- venules converge

1hree tunics

thin tunica media

thic tunica e"terna

Capacitance vessels or blood reservoirs

contain 34 of the blood supply


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Venous &"stem- Veins

# B., thinner walls, 5 lumen than arteries

Valves

Varicose veins

Venous sinuses % speciali6ed, flattened veins

e"tremely thin walls

coronary sinus of the heart dural sinuses of the brain


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Blood Flo#

Volume of blood flowing through a vessel, an

organ, or the entire circulation in a given period9

7n ml!min

= cardiac output (CO), for entire circulation Constant at rest /fairly0

Varies widely through individual organs


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Blood *ressure (B*)

*orce per unit area e"erted on wall of blood vessel

by contained blood

7n mm :g

easured in reference to systemic arterial B. inlarge arteries near the heart

1he differences in B. within the vascular system

provide the driving force that eeps blood moving

from higher to lower pressure areas


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*eri!heral 0esistance

Amt of friction blood encounters thru systemic

circulation

'ources9

1. Blood viscosity ( stic!iness, ")

2 1otal blood vessel length /5 length, 5 &0

) Blood vessel diameter

varies inversely with


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0esistance Factors- Blood Vessel iameter

a>or determinates - 'mall-diameter arterioles

& 5 when diameter # b!c more of the fluid contacts

the vessel wall of smaller vessels than larger ones

5 diameter changes in small arterioles than large

#therosclerosis$

1urbulent blood flow- opposite of smooth

$ramatically increase resistance due to turbulence


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Blood Flo#2 Blood *ressure2 and 0esistance

Blood flow /*0 - directly proportional to ∆ P

between two points in the circulation /B.0

5 B. , > *

# B. , < *

* - inversely proportional to resistance /&0

", % &

& is more important than ∆ P in influencing local blood pressure


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&"stemic Blood *ressure

1he pumping action of the heart generates blood flow

.ressure results when flow is opposed by resistance

'ystemic pressure

7s highest in the aorta

$eclines throughout the pathway

7s ? mm :g in the right atrium

1he steepest drop occurs in arterioles


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&"stemic Blood *ressure

Figure 19.3


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'rterial Blood *ressure

'ystolic pressure % arterial pressure during

ventricular contraction

$iastolic pressure % lowest arterial pressure

.ulse pressure % systolic minus diastolic pressure ean arterial pressure /A.0 % pressure that

propels the blood to the tissues

A. diastolic pressure (!) pulse pressure


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Factors 'iding Venous 0eturn

.assive return- not pusatile

&espiratory pumpD % breathing drives return

uscular pumpD % seletal muscle contractions

milD blood toward the heart

Valves prevent bacflow during venous return

*L'4*L'4 InterActive Physiology ®: 'natom" 0evie#-Blood Vessel &tructure and Function2 !ages ,56


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Factors 'iding Venous 0eturn

Figure 19.7


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ardiac 8ut!ut (8)

Eeural F :ormonal controls

&esting :&- vagus nerves; slow rate

'troe volume controlled by venous return /@$V0

ith stress9 the cardioacceleratory center increasesheart rate and stroe volume

1he end systolic volume /@'V0 decreases and

A. increases


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+aintaining B*- ardiac 8ut!ut (8)

Figure 19.6


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+aintaining B*- ontrols

'hort-term controls9

Eeural9

Baroreceptors

Chemoreceptors

Counteract moment-to-moment fluctuations in

blood pressure by altering peripheral resistance

+ong-term controls regulate blood volume


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Vasomotor fibers

stimulate

vasoconstriction

&timulate

vasomotor center

8 and R return blood

!ressure to

homeostaticrange

*eri!heralresistance (R )

ardiacout!ut

(8)

&timulus-

0ising blood!ressure

&"m!athetic

im!ulses to heart

( 0 and contractilit")

Im!ulses from

barorece!tors-&timulate cardio

accelerator" center (and inhibit cardio

inhibitor" center)

&timulus-

ecliningblood !ressure

'rterial blood !ressurefalls belo# normal range

Barorece!tors in

carotid sinusesand aortic archinhibited

omeostasis- Blood !ressure in normal range

Barorece!torsin carotid

sinuses and

aortic archstimulated

'rterialblood !ressure

rises abovenormal range

Im!ulse traveling along

afferent nerves from

barorece!tors-&timulate cardio

inhibitor" center

(and inhibit cardioaccelerator" center)

0ate of vasomotor im!ulses allo#svasodilation

( vessel diameter)

&"m!atheticim!ulses to

heart( 0 and contractili t")

R

8

8 and R

return blood!ressure to

omeostatic

range

Inhibitvasomotor center

I m b a l a n c e

I m b a l a n c e

Figure 19.:

'aintaining B$

eural control$

Baroreceptor

refle*es


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+aintaining B*- ;eural ontrols- hemorece!tors

Chemoreceptors in carotid and aorta

# o*ygen, % p+, carbon dio*ide

5 CO, 5 vasoconstriction


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B* control b" igher Brain enters

hile refle"es that routinely regulate B. are

integrated in medulla, these controls can be in turn be influenced by the corte" F hypothalamus

Corte" and :ypothalamus can modify B. via

relays to medullary centers


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+aintaining B*- hemicals that increase B*

Eorepinephrine and epinephrine

Antidiuretic hormone /A$:0

Angiotensin 77

@ndothelin and prostaglandin-derived growthfactor /.$G*0

All cause vasoconstriction


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+aintaining B*- Longerm +echanisms- 0enal

Controls B. by controlling blood volume

5 B., 5 water loss by idneys; lowers B.

# B., # water loss by idneys9 raises B.

Controls B. by controlling renin-angiotensin

mechanism

InterActive Physiology ®:

Blood *ressure 0egulation2 !ages ,5,<


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=idne" 'ction and Blood *ressure

Figure 19.9


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+'* Increases

Figure 19.1<

Blood

doping


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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsFigure 19.11

'ctivit" of muscular !um! andres!irator"

!um!

0elease

of ';*

Fluid loss from

hemorrhage2

excessive

s#eating

risis stressors-

exercise2 trauma2

bod"

tem!erature

Bloodborne

chemicals-

e!ine!hrine2

;E2 '2

angiotensin II>

';* release

Bod" si?e

onservation

of ;a@ and

#ater b" $idne"

Blood volume

Blood !ressureBlood !2 82

8

eh"dration2

high hematocrit

Blood

volumeBarorece!tors hemorece!tors

Venous

return'ctivation of vasomotor and cardiac

acceleration centers in brain stem

eart

rate

&tro$e

volume

iameter of

blood vessels

Cardiac output

Initial stimulus

0esult

*h"siological res!onse

Mean systemic arterial blood pressure

Blood

viscosit"

Peripheral resistance

Blood vessel

length


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+onitoring irculator" Efficienc"

Vital signs9

pulse

blood pressure

respiratory rate

body temperature

.ulse9 pressure wave caused by the e"pansion and

recoil of arteries

&adial pulse /taen at the wrist0 routinely used


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*al!ated *ulse

Figure 19.11


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Variations in Blood *ressure

Cycles over a 2


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'lterations in Blood *ressure

:ypotension % systolic pressure # (?? mm :g

:ypertension % (


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"!otension

Orthostatic hypotension % temporary low B. and

di66iness when suddenly rising from a sitting orreclining position

Chronic hypotension % hint of poor nutrition and

warning sign for AddisonKs disease

Acute hypotension % important sign of circulatory

shoc

1hreat to patients undergoing surgery and those in

intensive care units


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"!ertension

:ypertension maybe transient or persistent

.rimary or essential hypertension % (


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Blood Flo# hrough Bod" issues

Blood flow /tissue perfusion0 is involved in

$elivery of O2 and nutrients to, and removal of

wastes from, tissue cells

Gas e"change /lungs0

Absorption of nutrients /digestive tract0

Lrine formation /idneys0

"ate of flow is precisely the right amount to

provide for proper function


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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsFigure 19.1,

Brain

eart

&$eletal

muscles

&$in

=idne"

'bdomen

8ther

otal blood flo# during strenuous

exercise 1623


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Velocit" of Blood Flo# *erfusion 0ates

Figure 19.1,

&ate inversely

proportional to=sec area

'low flow in

capillaries allows

for

gas!nutrient!waste

e"change


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ontrol of 'rteriolar &mooth +uscle

Figure 19.1/

3ilate

Constrict

CO""4C56O 5O O"676#8 98634::::


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issue *erfusion 'utoregulation

&egulation of blood flow thru tissues based on needs

via vasodilation of vessels 'hort-term9

etabolic % in response to O2, nutrients;

+esser response to9 M, :, .G@, lactic acid levels

yogenic- vascular smooth muscle responses to changes in B.

+ong-1erm9

Angiogenesis /production of more vessels0 in response to9

Coronary vessel occludes

:igh altitudes

i * f i B i


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issue *erfusion Brain

7n most tissues, response /autoregulation0 is

controlled by # o"ygen F 5 waste materials

6n brain$

% p+, CO = vasodilation; not as sensitive to

% O

yogenic controls9

vasodilate during # B. Vasoconstrict during 5 B.

i * f i L


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issue *erfusion - Lungs

7n lungs9

'hort pathway

Arteries!arterioles thin-walled, large lumens

+ower arterial pressure /2

% O. , vasoconstriction

O. , vasodilation

Allows for proper o"ygen loading in the lungs

ill E h f 0 i t d


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a!illar" Exchange of 0es!irator" ases and

;utrients

Figure 19.13.

ill E h Fl id + t


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a!illar" Exchange- Fluid +ovements

Eet *iltration .ressure /E*.09 % all the forces acting on a capillary bed

E*. /:.c % :.if 0 % /O.c % O.if 0

:.c Capillary hydrostatic pressure- pressure of blood against thecapillary walls /fluid inside to

outside0

:.if 7nterstitial fluid :ydrostatic pressure

O.c Capillary Oncotic pressure- osmotic pressure /fluid outside toinside0

O.if 7nterstitial fluid hydrostatic pressure

7f E*. high, then :. 5 O. F fluid moves out of capillaries

7f E*. low, then :. # O. F fluid moves into capillaries

At the arterial end of a bed, hydrostatic forces dominate /fluids flow out0; Atvenous end, oncotic forces dominate /fluids move in0

InterActive Physiology ®: #utoregulation and Capillary 3ynamics, pages -<

; t Filt ti * (;F*)


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;et Filtration *ressure (;F*)

Figure 19.17

i l t &h $


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irculator" &hoc$

Circulatory shoc % any condition in which blood

vessels are inade8uately filled and blood cannotcirculate normally

&esults in inade8uate blood flow to meet tissue

needs

i l t &h $


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irculator" &hoc$

1hree types include9

:ypovolemic shoc % results from large-scale

blood loss

Vascular shoc % poor circulation resulting from

e"treme vasodilation

Cardiogenic shoc % the heart cannot sustain

ade8uate circulation


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irculator" *ath#a"s

1wo distinct circulations

( .ulmonary circulation % short loop that runs from

the heart to the lungs and bac to the heart

2 'ystemic circulation % routes blood through a

long loop to all parts of the body and returns to the

heart

ifferences Bet#een 'rteries and Veins


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ifferences Bet#een 'rteries and Veins

#rteries eins

$eliveryBlood pumped from heartinto single systemic artery % the aorta

Blood returns via superior andinterior venae cavae and drainsheart via the coronary sinus

+ocation$eep, and protected bytissue

Both deep and superficial

.athways *air, clear, and defined Convergent interconnections

'upply!drainage .redictable supply$ural sinuses and hepatic portal

circulation

evelo!mental 's!ects


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1he endothelial lining of blood vessels arises from

mesodermal cells, which collect in blood islands Blood islands form rudimentary vascular tubes

through which the heart pumps blood by the fourthwee of development

*etal shunts /foramen ovale and ductus arteriosus0 bypass nonfunctional lungs

1he ductus venosus bypasses the liver 1he umbilical vein and arteries circulate blood to

and from the placenta



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Blood vessels are trouble-free during youth

Vessel formation occurs9

As needed to support body growth

*or wound healing

1o rebuild vessels lost during menstrual cycles

ith aging, varicose veins, atherosclerosis, and

increased blood pressure may arise

*ulmonar" irculation


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*ulmonar" irculation

Figure 19.1:b

&"stemic irculation


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&"stemic irculation

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SCIT 1408 Applied Human Anatomy and Physiology II - Vessels Chapter 19 A